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Carbon Monoxide – Why It’s Important You Understand This Household Threat

Published on: October 22, 2013

One of the silent dangers lurking in your home could be carbon monoxide (CO) that can cause a variety of problems from flu-like symptoms to death. Even if you don’t use any gas appliances, you can still be exposed to CO indoors without ever knowing it.

Where Does CO Come From?

CO is the by-product of incomplete combustion and it comes from gas appliances, fires in wood-stoves or fireplaces, charcoal and gas grills, gas lawn mowers and lawn equipment that uses fuel, and even electric ovens running through the self-cleaning cycle.

Homes with attached garages are at risk for higher CO levels if anyone idles the car inside the garage or operates combustion equipment inside it. You can also be exposed to CO when riding in a boat if you sit near the motor.

Unvented gas, oil or kerosene heaters and fireplaces give off carbon monoxide in small quantities, even though the manufacturers assure their safety for use indoors. They use oxygen meters inside them to automatically shut them off when the oxygen level in the room gets too low.

What Does It Do?

The CO molecule is slightly smaller than oxygen and it will replace oxygen in your blood, causing flu-like symptoms such as dizziness, nausea, headaches, sleepiness and eventually death, basically from suffocation. All air-breathing animals, including your pets, are susceptible to this toxic gas, especially people with heart or lung conditions and the young, elderly, pregnant women and fetuses.

How to Detect It

Since it’s invisible and odorless, the only way to detect it is with special CO detectors that sound an alarm when levels reach a certain point. Carbon monoxide detectors are available in home improvement and hardware stores and come in different styles.

If your home has older gas appliances, it’s a good idea to choose a CO detector that’s hardwired into your home’s wiring. These show periodic readings of the CO levels indoors, which are helpful to know when your gas appliances are in use, particularly your gas furnace. If the level climbs as the furnace runs, it’s a good idea to contact an HVAC professional immediately to diagnose the problem.

Some CO detectors plug into a wall outlet but unless they have a battery backup, won’t work in a power outage. If you have hearing impaired family members, use alarms that also use powerful strobe lights, along with a siren to alert family members to high carbon monoxide levels.

If you have family members who are more at risk for CO poisoning, you can purchase low-level meters that will sound an alarm at levels that otherwise wouldn’t be bothersome. Sensitive monitors will detect and report levels as low as 5 parts per million (ppm) and sound the alarm when levels get slightly higher than that. The U.S. EPA limit on outdoor CO is 9 ppm.

How to Place the CO Detectors

CO is slightly lighter than air, so the detectors need to be placed at eye level or higher. Each level of your home should have a CO detector, but if you have to budget for them, put the first one in the hallway by the master bedroom.

Those that run on batteries should be placed in a location where they’re easy to access so you can check the batteries monthly because they use more battery power than smoke detectors.

The detectors need to be from 12 to 15 feet away from appliances that use gas to minimize false alarms. If your home has an attached garage, the 12 to 15 foot suggestion also applies. Whenever a gas appliance turns on, it emits a small amount of CO and if the detector is too close, you’ll have too many false alarms. Humidity also interferes with their operation, so keeping them away from bathrooms and kitchens helps them function better.

What to Do When the Alarm Sounds

When the CO detector sounds, the best thing is to leave the building, making sure all occupants go outside as quickly as possible, including pets. Ask people how they feel and if any report symptoms, call 9-1-1 immediately. The fire department will respond and inspect your home for high levels of this gas, and also will provide medical services if it’s apparent that anyone has unhealthy CO blood levels.

If the levels are low and the alarm still sounds, you may need to replace the carbon monoxide detector. They do wear out and can malfunction.

HVAC Maintenance Helps

Many homeowners know it’s a good idea to have their HVAC equipment maintained annually to improve its operating efficiency and keep it clean. The annual service call, best performed at the start of the heating and cooling seasons, includes a visual inspection that will show any problems with the equipment.

Rust inside a furnace indicates improper operation and can lead to higher levels of carbon monoxide in your home. When gas burns, it creates water vapor and if the vapor condenses before exhausted through the flue, it will rust metal parts. If rust develops in the flue or on the heat exchanger, you could be at risk for CO poisoning.

Small cracks in the heat exchanger may not be serious, but holes that develop pose an immediate problem. The technician will have to disable the furnace until it’s repaired or replaced. This condition is known as a red-tagged furnace and laws require that the furnace be taken out of operation.

If you need to replace the furnace, choosing one with a sealed combustion chamber will increase indoor safety, since the air required for combustion and its by-products vents directly outside, eliminating the threat of CO poisoning from your heating system. Other types of furnaces also need adequate venting when they’re installed.

Dirt covering the heat exchanger in the furnace also weakens the metal from which the heat exchanger is made, so it’s a good idea to keep the air filter for your forced-air heating system clean. This helps the heat exchanger warm the air instead of retaining heat.

Ductwork leaks can also pull CO into your home by back-drafting, even in the summer if you have an attached garage where you park your vehicle or use vented gas appliances, like water heaters or dryers. Maintenance for your furnace or air conditioner should include a ductwork inspection.

You can also ask the HVAC contractor whether they use handheld detectors capable of detecting low levels of carbon monoxide in your air. They might use the meter to check the rest of your home’s appliances, as well. It’s important to note that CO levels change throughout the day, and tend to rise at night when your home is tightly closed for hours at a time.

Maintain These Appliances, Too

  • Periodically having your water heater professionally cleaned and maintained will lower the risk it presents for carbon monoxide poisoning. Professional maintenance also extends the tank life and lowers water heating costs.
  • If a gas stove has a yellow flame, it needs cleaning or adjustments.
  • Lint that collects on the dryer lint screen, below the dryer and in the vent pipe is also a fire hazard, and if it’s plugged, represents a CO hazard.

Consider Your Attached Garage

If you park your car in the garage or run the engine inside it, verify that the seal between the connecting door is weatherstripped. Check the common wall between the house and the garage and seal any leaks with caulk or expanding foam. If you routinely run your engine in the garage, install a ventilating fan to blow the exhaust outside.

If you’d like to learn more about carbon monoxide in your home, AC Southeast can put you in contact with a trusted HVAC contractor serving the southeastern U.S., including Florida, Georgia, Mississippi, South Carolina and Alabama.